CN108604622B - Light emitting device and light emitting device package including the same - Google Patents

Abstract

An embodiment of the light emitting device comprises: a substrate; a first conductive type semiconductor layer disposed on the substrate; an active layer disposed on the first conductive type semiconductor layer, a plurality of quantum well layers and a plurality of quantum barrier layers being alternately stacked in the active layer; a second conductive type semiconductor layer disposed on the active layer; a contact layer disposed on the second conductive type semiconductor layer; a current spreading layer disposed on the contact layer; and a current blocking layer disposed on the second conductive type semiconductor layer, wherein the contact layer and/or the current spreading layer may be formed to surround at least a portion of the current blocking layer and have a maximum intensity value of the diffracted X-ray beam when a miller plane index is 400.

Description

Light emitting device and light emitting device package including light emitting device

technical field

Embodiments relate to light emitting devices and light emitting device packages including the light emitting devices.

Background technique

The statements in this section merely provide background information related to the embodiments and may not constitute prior art.

III-V compound semiconductors such as GaN and AlGaN have been widely used in electronic and optoelectronic devices due to their many advantages such as wide range and easily tunable energy bandgap.

Specifically, light-emitting devices using III-V or II-VI compound semiconductor materials, such as light-emitting diodes LEDs or laser diodes, can emit various colors, such as red, green, due to the advancement of thin film growth technology and the development of device materials. , blue and ultraviolet light, etc. Light emitting devices can also efficiently emit white light using fluorescent materials or through a combination of colors. Compared with conventional light sources such as fluorescent lamps and incandescent lamps, light emitting devices have the advantages of low power consumption, semi-permanent lifetime, fast response time, safety, and environmental friendliness.

Accordingly, light emitting devices have been increasingly applied to transmission modules of optical communication devices, LED backlights to replace cold cathode fluorescent lamps (CCFLs) constituting the backlights of liquid crystal display (LCD) devices, white LED lighting to replace fluorescent lamps or incandescent lamps devices, headlights and signal lights of vehicles.

Research has been ongoing on light-emitting devices that operate smoothly and improve energy efficiency. For example, there has been a need to develop light emitting devices with low operating voltages and high light output.

SUMMARY OF THE INVENTION

technical problem

Accordingly, embodiments provide light emitting devices with low operating voltages and high light output.

The technical objects that can be achieved by the present invention are not limited to the content specifically described above, and other technical objects not described herein will be more clearly understood by those skilled in the art from the following detailed description.

Technical solutions

In one embodiment, a light emitting device may include: a substrate; a first conductivity type semiconductor layer arranged on the substrate; an active layer arranged on the first conductivity type On the semiconductor layer, a plurality of quantum well layers and a plurality of quantum barrier layers are alternately stacked in the active layer; a second conductive type semiconductor layer, the second conductive type semiconductor layer is arranged on the active layer; a contact layer , the contact layer is arranged on the second conductivity type semiconductor layer; the current spreading layer is arranged on the contact layer; and the current blocking layer is arranged on the second conductivity type semiconductor layer, wherein the contact layer and/or the current spreading layer is formed to surround at least a portion of the current blocking layer and has a maximum intensity value of a diffracted X-ray beam when the Miller plane index is 400 .

In another embodiment, a light emitting device may include: a reflective layer; a substrate arranged on the reflective layer; a first conductive type semiconductor layer arranged on the substrate; an active layer, which is arranged on the first conductivity type semiconductor layer; a second conductivity type semiconductor layer, which is arranged on the active layer; and a contact layer, which is arranged on the first conductivity type semiconductor layer. on the two-conductivity-type semiconductor layer; and a current spreading layer arranged on the contact layer and formed of an indium tin oxide (ITO) material; a passivation layer arranged on the current spreading layer; a first electrode arranged on the first conductivity type semiconductor layer; a second electrode arranged on the second conductivity type semiconductor layer; and a current blocking layer arranged on the between the second conductive type semiconductor layer and the second electrode.

In one embodiment, a light emitting device package may include: a body including a cavity; a lead frame mounted on the body; and a light emitting device electrically connected to the lead frame.

beneficial effect

In the embodiment, the contact layer functions to smoothly inject holes from the second conductive type semiconductor layer to the active layer, so that the light emitting device of the embodiment can reduce the operating voltage and increase the light output.

In an embodiment, the current spreading layer of the ITO material having the non-stoichiometric structure reduces current resistance, so that the current supplied from the second electrode spreads uniformly to the current spreading layer, and as a result, the operating voltage of the light emitting device is reduced by is reduced and the light output of the light emitting device is increased.

Description of drawings

1a is a cross-sectional view of a light emitting device according to an embodiment.

FIG. 1b is a cross-sectional view of a light emitting device including a passivation layer having a different structure from that of FIG. 1a.

FIG. 2 is a schematic plan view of a light emitting device according to an embodiment.

Figure 3 is an enlarged view of part A of Figures 1a and 1b.

Figure 4 is an enlarged view of part B of Figures 1a and 1b.

Figure 5 is an enlarged view of part C of Figures 1a and 1b.

6 and 7 are graphs showing experimental results for explaining X-ray diffraction of the light emitting device according to the embodiment.

8 and 9 are graphs showing the experimental results of Table 2. FIG.

10 and 11 are graphs showing the experimental results of Table 3. FIG.

FIG. 12 is a view illustrating the light emitting device package 10 according to the embodiment.

Detailed ways

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the accompanying drawings. However, the present disclosure should not be construed as limited to the embodiments set forth herein, but on the contrary, this disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the embodiments.

Although terms such as "first," "second," etc. may be used to describe various components, these components should not be limited by the above terms. The above terms are only used to distinguish one component from another. In addition, terms specifically defined in consideration of the configuration and operation of the embodiments are only used to describe the embodiments, and do not limit the scope of the embodiments.

In the description of the embodiments, it will be understood that when an element is referred to as being formed "on" or "under" another element, it can be directly formed "on" or "under" the other element or be indirectly formed therebetween. intermediate element. It will also be understood that when an element is referred to as being "on" or "under", "under the element" as well as "on the element" can be included based on the element.

As used herein, any physical or logical relationship or order between such entities or elements such as "on"/"upper"/"over", "below"/" is not necessarily required or implied. Relational terms such as "lower"/"under" are only used to distinguish one entity or element from another entity or element.

1a is a cross-sectional view of a light emitting device according to an embodiment. FIG. 1b is a cross-sectional view of a light emitting device including a passivation layer 220 having a different structure from that of FIG. 1a. FIG. 2 is a schematic plan view of a light emitting device according to an embodiment.

The light emitting device of this embodiment may include a substrate 110, a first conductive type semiconductor layer 120, an active layer 130, a second conductive type semiconductor layer 140, a contact layer 150, a current spreading layer 160, a first electrode 170, a second electrode 180 , the current blocking layer 190 , the reflective layer 210 and the passivation layer 220 .

The first conductive type semiconductor layer 120 , the active layer 130 and the second conductive type semiconductor layer 140 may constitute a light emitting structure.

The substrate 110 may support the light emitting structure. The substrate 110 may be any one of a sapphire substrate, a silicon (Si) substrate, a zinc oxide (ZnO) substrate, and a nitride semiconductor substrate, or may be at least one of GaN, InGaN, AlGaN, or AlInGaN thereon A stacked template substrate.

A light emitting structure may be arranged on the substrate 110 and used to generate light. In this case, the difference in lattice constant and thermal expansion coefficient between the substrate 110 and the light emitting structure may cause stress around the boundary surface between the substrate 110 and the light emitting structure.

To alleviate such stress, a buffer layer (not shown) may be interposed between the substrate 110 and the light emitting structure. In addition, in order to improve the crystallinity of the first conductive type semiconductor layer 120, an undoped semiconductor layer (not shown) may be interposed between the substrate 110 and the light emitting structure. Notably, N-vacancy may be formed during the fabrication process, and then doping may be performed unintentionally.

Here, the buffer layer can be grown at low temperature. The buffer layer may be a GaN layer or an AlN layer, but the embodiment is not limited thereto. Except that the undoped semiconductor layer has a lower conductivity than the first conductivity type semiconductor layer 120 (because the undoped semiconductor layer is not doped with n-type dopant), the undoped semiconductor layer may be similar to the first conductivity type semiconductor layer 120. The semiconductor layers 120 of the same conductivity type are the same.

As illustrated in FIG. 1 a , the first electrode 170 may be disposed on the exposed stepped portion of the first conductive type semiconductor layer 120 , and the second electrode 180 may be disposed on the upper exposed portion of the second conductive type semiconductor layer 140 . The light emitting device of the present embodiment may emit light if current is applied through the first electrode 170 and the second electrode 180 .

Although FIGS. 1 a and 1 b illustrate a light emitting device having a horizontal structure, a light emitting device having a vertical structure or a flip-chip structure may also be provided.

As described above, the light emitting structure may include the first conductive type semiconductor layer 120 , the active layer 130 and the second conductive type semiconductor layer 140 .

The first conductive type semiconductor layer 120 may be disposed on the substrate 110 and may be formed of, for example, a nitride semiconductor.

That is, the first conductive type semiconductor layer 120 may be composed of a semiconductor selected from the group consisting of InxAlyGa1 _{-xyN ( 0≤x≤1} , 0≤y≤1 and 0≤x+y≤1) The material is formed of, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and AlInN, and may be doped with an n-type dopant such as Si, Ge, Sn, Se, or Te.

The active layer 130 may be disposed on the first conductive type semiconductor layer 120 and generated by energy generated during recombination of electrons and holes supplied from the first conductive type semiconductor layer 120 and the second conductive type semiconductor layer 140, respectively. Light.

The active layer 130 may be formed of a compound semiconductor, eg, a group III-V or group II-VI compound semiconductor, and may have a single quantum well structure, a multiple quantum well structure, a quantum wire structure, or a quantum dot structure.

When the active layer 130 has a quantum well structure, the active layer 130 may have a single quantum well structure or a multi-quantum well structure including a structure having InxAlyGa1 _{-xyN (} 0≤x≤1, _0≤y≤ Quantum well layer with composition of 1 and 0≤x+y≤1) and composition with In _a Al _b Ga _1-ab N (0≤a≤1,0≤b≤1 and 0≤a+b≤1) the quantum barrier layer.

In this case, the energy band gap of the quantum well layer may be smaller than that of the quantum barrier layer. When the active layer 130 of the embodiment has a multi-quantum well structure, the active layer 130 may include a structure in which a plurality of quantum well layers and a plurality of quantum barrier layers may be alternately stacked.

The second conductive type semiconductor layer 140 may be arranged on the active layer 130 . The second conductive type semiconductor layer 140 may be formed of, for example, a nitride semiconductor.

That is, the second conductive type semiconductor layer 140 may be composed of a semiconductor selected from the group consisting of InxAlyGa1 _{-xyN ( 0≤x≤1} , 0≤y≤1 and 0≤x+y≤1) The material is formed of, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and AlInN, and may be doped with a p-type dopant such as Mg, Zn, Ca, Sr, or Ba.

The contact layer 150 may be disposed on the second conductive type semiconductor layer 140, and may serve to improve the contact performance between the current spreading layer 160 disposed thereon and the second conductive type semiconductor layer 140 disposed thereunder, so that the air is empty. Holes may be smoothly injected into the active layer 130 from the second conductive type semiconductor layer 140 .

That is, the contact layer 150 is arranged at the boundary surface between the current spreading layer 160 and the first conductivity type semiconductor layer 120 and serves to reduce the possibility of being between the current spreading layer 160 and the second conductivity type semiconductor layer 140 The electrical resistance generated at the boundary surface of , so that the current supplied to the current spreading layer 160 can smoothly flow into the second conductive type semiconductor layer 140 .

In this way, current may smoothly flow into the second conductive type semiconductor layer 140 , and then, a large number of holes may be generated from the second conductive type semiconductor layer 140 and injected into the active layer 130 .

In the embodiment, the contact layer 150 may smoothly inject holes from the second conductive type semiconductor layer 140 into the active layer 130, so that the operating voltage is lowered and the light output is improved in the light emitting device according to the embodiment.

The contact layer 150 may be formed of, for example, at least one material of indium tin oxide (ITO), NiO, or NiAu, and may be formed in a structure having a low electrical impedance.

In order to form the contact layer 150 having a low electrical impedance structure, the porosity of, for example, oxygen (O ₂ ) components may be appropriately increased. Oxygen may be included in the components constituting the contact layer 150 , and oxygen tends to increase the electrical impedance of the contact layer 150 .

Therefore, in order to reduce the electrical impedance of the contact layer 150, the contact layer 150 may be appropriately formed to have a non-stoichiometric structure in which an oxygen component is lacking, rather than a stoichiometric structure with high oxygen porosity.

During the deposition of the contact layer 150, a process gas including argon can be used without mixing oxygen to achieve a non-stoichiometric structure lacking the oxygen component.

That is, oxygen gas is not included in the process gas, so that only the oxygen component included in the source material may be included in the contact layer 150 . Because there is no additional supply of oxygen through the process gas, the contact layer 150 may be formed as a non-stoichiometric structure lacking oxygen components.

However, in order to improve the light transmittance of the contact layer 150, for example, a process gas in which oxygen and/or hydrogen (H ₂ ) is mixed with argon may be used. When an X-ray diffraction test of the contact layer 150 is performed, the crystal structure with the maximum intensity value of the diffracted beam may be provided at a Miller plane index of 222 or 400.

The current spreading layer 160 may be disposed on the contact layer 150 and may be electrically connected to the second electrode 180 . The current spreading layer 160 may function because the current applied from the second electrode 180 may spread uniformly over the entire surface of the second conductive type semiconductor layer 140 .

If the current applied to the second conductive type semiconductor layer 140 through the second electrode 180 spreads unevenly, the current may be concentrated at a specific portion of the second conductive type semiconductor layer 140 . As a result, holes injected from the second conductive type semiconductor layer 140 into the active layer 130 may be concentrated in a specific portion of the active layer 130 .

The concentration of hole injection can significantly degrade the light output of the light emitting device. In order to prevent this, it may be appropriate to spread the current uniformly over the entire surface of the second conductive type semiconductor layer 140 through the current spreading layer 160 .

The current spreading layer 160 may be formed of ITO. As described above, the electrical impedance of the current spreading layer 160 needs to be reduced on the contact layer 150 as described above.

Therefore, since oxygen in the components constituting the current spreading layer 160 tends to increase the electrical impedance, in order to reduce the electrical impedance of the current spreading layer 160, the current spreading layer 160 may be appropriately formed to have a non-stoichiometric structure lacking an oxygen component , rather than a stoichiometric structure with high oxygen porosity. The method of forming the non-stoichiometric structure lacking the oxygen component will be described in detail later.

The current blocking layer 190 may be disposed on the second conductive type semiconductor layer 140 , that is, between the second conductive type semiconductor layer 140 and the second electrode 180 . Here, the area of the current blocking layer 190 may be formed to be larger than that of the second electrode 180 .

The contact layer 150 and/or the current spreading layer 160 may be provided to surround at least a portion of the current blocking layer 190 . For example, referring to FIG. 4 , the contact layer 150 and/or the current spreading layer 160 may be formed to surround the upper surface of the current blocking layer 190 and/or the side surface of the current blocking layer 190 .

The current blocking layer 190 may function to prevent the current applied from the second electrode 180 from being concentrated in a portion of the second conductive type semiconductor layer 140 facing the second electrode 180 .

This is because the current blocking layer 190 prevents current from flowing from the second electrode 180 into the second conductive type semiconductor layer 140 immediately. To this end, the current blocking layer 190 may be formed of, for example, an electrically insulating material.

The current blocking layer 190 may prevent current from being concentrated at a specific portion of the second conductive type semiconductor layer 140 , and thus, prevent holes injected from the second conductive type semiconductor layer 140 into the active layer 130 from being concentrated in the active layer 130 of the specific portion, so that deterioration of the light output of the light emitting device of the embodiment can be prevented.

That is, the current blocking layer 190 may function to uniformly spread the current on the current spreading layer 160 , and the current may be concentrated at the portion facing the second electrode 180 in the vertical direction.

As shown in FIGS. 1a and 1b , a mesa in which the second electrode 180 is arranged may be formed in the light emitting device, and a distance L1 from the mesa to the first electrode 170 may be, for example, 3 μm to 10 μm.

Here, the mesa represents a protruding portion in the light emitting device, and the distance L1 represents the distance from the side surface of the first conductive type semiconductor layer 120 of the mesa to the point of the first electrode 170 of the nearest side surface of the first conductive type semiconductor layer 120 .

As shown in FIG. 2 , the second electrode 180 may include the second branch electrode 181 formed on the current spreading layer 160 , and the first electrode 170 may include the first branch electrode 171 formed on the first conductive type semiconductor layer 120 .

Notably, the portion where the first branch electrode 171 is formed may be formed to have a structure in which the current spreading layer 160, the second conductive type semiconductor layer 140, and the active layer 130 may be etched in a vertical direction so as to facilitate the first branch The electrode 171 is not electrically connected to the current spreading layer 160 , the second conductive type semiconductor layer 140 and the active layer 130 .

In this case, the current blocking layer 190 may also be formed in a portion facing the second branch electrode 181 in the vertical direction. This serves to uniformly spread the current on the current spreading layer 160 by preventing the current from flowing concentratedly in the vertical direction through the first branch electrode 171 into the second conductive type semiconductor layer 140 facing the first branch electrode 171 .

The distance from the mesa to the first branch electrode 171 may be smaller than the distance L1 from the mesa to the first electrode 170 .

The reflective layer 210 may be disposed under the substrate 110 and may serve to improve the luminous efficiency of the light emitting device. That is, a part of the light emitted from the active layer 130 may be emitted through the lower portion of the substrate 110 . In consideration of this, the reflective layer 210 may be disposed under the substrate 110 so as to reflect light emitted through the lower portion of the substrate 110 and transmit the light in the upward direction of the light emitting device. As a result, the light emitting efficiency of the light emitting device can be improved.

The reflection layer 210 may be a distributed Bragg reflection layer having a multi-layer structure in which at least two layers having different refractive indices are alternately stacked at least once. The reflective layer 210 reflects light introduced from the light emitting structure.

That is, the reflection layer 210 may have a structure in which a first layer having a relatively high refractive index and a second layer having a relatively low refractive index are alternately stacked. In this case, the reflectivity of the reflective layer 210 may be different according to the difference between the reflection index of the first layer and the second layer and the thickness of each of the first layer and the second layer.

At least a portion of the passivation layer 220 may be disposed on the current spreading layer 160 . Specifically, as shown in FIG. 1 a , the passivation layer 220 may be disposed at the upper surface of the current spreading layer 160 and the upper surface of the stepped portion of the first conductive type semiconductor layer 120 .

In addition, the passivation layer 220 may be disposed at at least a portion of the side surfaces of the first conductive type semiconductor layer 120 , the active layer 130 , the second conductive type semiconductor layer, and the current spreading layer 160 .

The passivation layer 220 having the above structure may serve to protect each layer constituting the light emitting device. In particular, the passivation layer 220 may function to prevent an electrical short between the first conductive type semiconductor layer 120 and the second conductive type semiconductor layer 140 .

As an example, the passivation layer 220 may be formed not to cover a portion of the side surface of the first conductive type semiconductor layer 120, as shown in FIG. 1a. As another example, the passivation layer 220 may be formed to cover all side surfaces of the first conductive type semiconductor layer 120 as shown in FIG. 1b.

The thickness of the passivation layer 220 may be about 100 nm. According to the thickness of the passivation layer 220, the refractive index of the light emitting structure may vary. Therefore, the luminous efficiency of the light emitting device, that is, the light extraction efficiency of the light emitting device, may vary according to the thickness of the passivation layer 220 .

As an example, the passivation layer 220 may be provided to expose side surfaces of the first and second electrodes, as shown in FIGS. 1 a and 1 b. As another example, the passivation layer 220 may be provided to cover the side surfaces of the first and second electrodes. As yet another embodiment, the passivation layer 220 may be provided such that the side surfaces of the passivation layer 220 are spaced apart from the side surfaces of the first and second electrodes by a predetermined distance. However, embodiments are not limited thereto.

Figure 3 is an enlarged view of part A of Figures 1a and 1b. As shown in FIG. 3 , the current spreading layer 160 may be stacked on the contact layer 150 .

The contact layer 150 may be formed to have a thickness T1 of, for example, 1 nm to 5 nm. For example, the current spreading layer 160 may be formed to have a thickness T2 of 20 nm to 70 nm. However, the thickness of the contact layer 150 at the portion where the current blocking layer 190 is arranged may be different from the above-described thickness T1.

The ratio of the thickness of the current blocking layer 190 to the total thickness of the contact layer 150 and the current spreading layer 160 may be, for example, 2:1 to 5:1 (thickness of the current blocking layer 190 : total thickness). However, embodiments are not limited thereto.

The ratio of the thickness of the current spreading layer 160 to the thickness of the contact layer 150 may be, for example, 6:1 to 10:1 (thickness of the current spreading layer 160 : thickness of the contact layer 150 ). However, embodiments are not limited thereto.

If the thickness of the current spreading layer 160 is less than 20 nm, the electrical impedance of the current spreading layer 160 rises, and then the operating voltage of the light emitting device also rises. This may have an adverse effect on the performance of the light emitting device.

If the thickness T2 of the current spreading layer 160 exceeds 70 nm, the light transmittance of the current spreading layer 160 is reduced, and then the light output of the light emitting device is reduced. This may adversely affect the performance of the light emitting device.

The passivation layer 220 may be provided with a thickness T5 of about 100 nm, as described above, and may be thicker than the contact layer 150 and/or the current spreading layer 160 .

The ratio of the thickness T5 of the passivation layer 220 to the thickness T2 of the current spreading layer 160 may be, for example, T5:T2=1.4:1 to 5:1.

As described above, the current spreading layer 160 may be formed of ITO. To reduce electrical impedance, the current spreading layer 160 may have a non-stoichiometric structure lacking oxygen components.

The current spreading layer 160 may be formed into a stack by, for example, plasma vacuum deposition. The non-stoichiometric structure of the current spreading layer 160 may be formed by the scheme described below.

The current spreading layer 160 may be formed by deposition under an argon (Ar) atmosphere. That is, by spraying the source material constituting the current spreading layer 160 on the contact layer 150 by a process gas in a plasma state, the deposition process of the current spreading layer 160 can be performed at a high temperature. This plasma vacuum deposition can be performed in a vacuum chamber.

One method of plasma vacuum deposition includes sputtering. When ions contained in a process gas in a plasma state apply an impact to a source material, ie, a target material, sputtering may be performed by ejecting atoms and/or molecules from the target material to form a thin film.

Sputtering is excellent in the adhesion of thin films, and can form thin films with uniform thickness and uniform density because the target material is widely distributed in the vacuum chamber. Thin films formed by sputtering have advantages such as excellent step coverage and easy deposition of oxide series materials.

The process gas may include an inert gas such as argon. Typically, a mixture of argon and oxygen or a mixture of argon, oxygen and hydrogen can be used as the process gas for depositing ITO.

However, when a gas mixed with oxygen is used as the process gas, oxygen is sufficiently supplied to the deposited ITO. Then, ITO in which oxygen is contained stoichiometrically can be stacked.

The stoichiometric structure of ITO has the characteristics of high electrical impedance due to the oxygen contained therein. Therefore, the current spreading layer 160 of an embodiment formed of an ITO material may use argon as a process gas in order to reduce its electrical impedance.

When argon is used, the oxygen porosity of the current spreading layer 160 may increase. Since the oxygen holes are used as electron carriers in the current spreading layer 160, the electrical impedance of the current spreading layer 160 can be reduced.

As another example, the process gas may use an oxygen-free inert gas alone or a mixture of various types of inert gas.

When the current spreading layer 160 of ITO material is formed using a process gas containing argon and no oxygen, the current spreading layer 160 may be formed as a non-stoichiometric structure that is stoichiometrically deficient in oxygen.

In this case, when the Millar plane index in the X-ray diffraction experiment is 400, the current spreading layer 160 may have the maximum intensity value of the diffracted beam.

Table 1 shows experimental result values of the impedance of the current spreading layer 160 of the ITO material of the embodiment. In Table 1, the comparative samples refer to samples when the current spreading layer 160 is formed using a process gas in which argon is mixed with oxygen, and the example samples refer to when the current spreading layer 160 is formed using a process gas including only argon sample. Here, the impedance refers to sheet resistance. Therefore, the impedance unit is Ω/□.

The experimental values of the samples have been measured when the thickness T2 of the current spreading layer 160 is about 40 nm, 50 nm and 60 nm. The experiment was performed multiple times, and the impedance value was an average value of the values obtained through the multiple experiments.

[Table 1]

Sample/ITO thickness (nm) Impedance value (Ω/□) Transmittance(%) Compare Samples/40 78.32 94.39 Example sample/40 50.83 94.92 Compare Samples/50 53.25 92.84 Example sample/50 32.55 92.39 Compare Samples/60 49.03 92.29 Example sample/60 24.01 92.24

Referring to Table 1, it can be understood that the impedance values of the example samples are significantly lower than those of the comparative samples. That is, the current spreading layer 160 formed by using the process gas including only argon has a significantly lower resistance value than the current spreading layer 160 of the ITO material formed by using the process gas including the mixture of argon and oxygen. Therefore, it can be understood that when the current spreading layer 160 of the embodiment is used, the current supplied from the second electrode 180 can be spread on the current spreading layer 160 more uniformly.

In terms of light transmittance, with respect to the current spreading layer 160 of the same thickness, the light transmittance difference between the comparative sample and the example sample is small. Therefore, it can be clearly understood that the electrical impedance of the current spreading layer 160 of the non-stoichiometric structure of the ITO material according to the embodiment is greatly reduced, but the light transmittance is hardly changed.

That is, when the current spreading layer 160 is formed using a process gas including only argon, since the electrical impedance is reduced and the light transmittance is not lowered, the light output of the light emitting device can be improved.

In an embodiment, the current supplied from the second electrode 180 is uniformly distributed on the current spreading layer 160 because the current spreading layer 160 of the ITO material of the non-stoichiometric structure has a reduced current resistance. As a result, the operating voltage of the light emitting device is lowered and the light output of the light emitting device is increased.

Figure 4 is an enlarged view of part B of Figures 1a and 1b. In an embodiment, the current blocking layer 190 may be formed to have a thickness T3 of, for example, 90 nm to 150 nm.

As shown in FIG. 4 , the contact layer 150 and the current spreading layer 160 may be sequentially stacked in an upward direction from the bottom between the current blocking layer 190 and the second electrode 180 .

In this case, in order to secure a space for arranging the current blocking layer 190, the thickness of each side surface of the contact layer 150 and the current spreading layer 160, that is, the thickness of each other portion of the contact layer 150 and the current spreading layer 160 In comparison, the thickness of each side surface of the current spreading layer 160 and the contact layer 150 at the side surfaces of the current blocking layer 190 may be formed thin.

In another embodiment, in order to secure a space in which the current blocking layer 190 is arranged, the current spreading layer 160 may be formed only between the current blocking layer 190 and the second electrode 180 .

As described above, the area of the current blocking layer 190 may be larger than that of the second electrode 180 . Here, the distance L2 between the end of the second electrode 180 and the current blocking layer 190 may be about 3 μm.

Figure 5 is an enlarged view of part C of Figures 1a and 1b. That is, in the mesa region in which the second electrode is formed, the distance T4 between the side surface of the current spreading layer 160 and/or the contact layer 150 and the side surface of the second conductive type semiconductor layer 140 may be, for example, 3 μm to 10 μm.

If the distance T4 is less than 3 μm, electron transitions may occur in the current spreading layer 160 , the side surface of the contact layer 150 and/or the side surface of the second conductive type semiconductor layer 140 , and thus, current leakage may occur.

If the distance T4 exceeds 10 μm, the operating voltage of the light emitting device can be increased and the light output of the light emitting device can be reduced.

6 and 7 are diagrams showing experimental results for explaining X-ray diffraction of the light emitting device according to the embodiment. The X-ray diffraction experiment is a result of analyzing the type of diffracted beam by irradiating the current spreading layer 160 with the X-ray beam.

In the graph, the horizontal axis represents the diffraction angle (°) of the X-ray beam diffracted by irradiating the current spreading layer 160 with the X-ray beam, and the vertical axis represents the intensity (a.u) of the diffracted X-ray beam.

In FIGS. 6 and 7 , the case is actually shown in which the process gas includes argon, the process gas includes a mixture of argon and oxygen, and the process gas includes a mixture of argon, oxygen, and hydrogen. Figure 6 actually shows the intensity of the diffracted beam in each case. Figure 7 shows approximately matched non-peak values of diffracted beam intensities under various conditions to facilitate comparison of peaks in diffracted beam intensities under various conditions.

In the drawings, numerals 222, 400 and 440 represent Miller plane indices. The Miller plane index represents a specific crystal plane of the current spreading layer 160 that is an experimental target. Therefore, when the peaks of the intensities of the diffracted beams are different in the portions where the Miller plane indices are equal, this may mean that the crystal structures are different.

6 and 7 , the current spreading layer 160 formed by deposition in an Ar atmosphere may have a plurality of peaks in the intensity of the diffracted beam according to the Millar plane index in the X-ray diffraction experiment.

Referring to FIG. 7 , when the Miller plane index is 222, in the case where the process gas is a mixture of argon and oxygen, the intensity of the diffracted beam has a peak. When the Miller plane index is 400, in the case where the process gas is argon, the intensity of the diffracted beam has a peak. That is, in the embodiment, when the Millar plane index is 400 in the X-ray diffraction experiment, the current spreading layer 160 may have the maximum intensity peak of the diffracted beam.

Therefore, according to the Millar plane index in the X-ray diffraction experiment of the current spreading layer 160, the composition of the process gas can be identified through the intensity peak distribution of the diffracted beam.

As described above, when the current spreading layer 160 is deposited by a sputtering process using argon as a process gas, the current spreading layer 160 may be formed into a structure having an oxygen component with high porosity. Then, the electrical impedance of the current spreading layer 160 is reduced so that the current can spread smoothly on the current spreading layer 160 .

Tables 2 and 3 show operating values and experimental values of light output of light-emitting chips using the light-emitting devices of the Examples. Each light-emitting chip was tested with a rated output of 95mA.

In Table 2, the size of all light-emitting chips is 1200×600. Case 1 is a case where the operating voltage and light output are measured at the center of the light emitting device, and Case 2 is a case where the operating voltage and light output are measured at a specific portion separated from the center of the light emitting device. A light emitting device including a current spreading layer 160 having an ITO material with a thickness of about 40 nm was used.

Test 1 corresponds to a test when using the current spreading layer 160 of a common ITO material, that is, when using a mixture of argon and oxygen as a process gas and using a light emitting device of a structure in which the contact layer 150 is not formed.

Test 2 corresponds to a test when using the current spreading layer 160 of the ITO material of the embodiment, that is, when using argon as a process gas not containing oxygen and using a light emitting device having a structure in which the contact layer 150 is formed.

[Table 2]

In Table 3, a light-emitting chip having a size of 1200×700 was used, and other conditions were the same as those described in Table 2.

[table 3]

Considering the test results, the working voltage in Test 2 is lower than that of Test 1, and the light output in Test 2 is higher than that in Test 1.

Therefore, it can be understood that when using the light emitting device of the embodiment in which the current spreading layer 160 of the ITO material of the non-stoichiometric structure is formed and the contact layer 150 is formed, the current spreading layer 160 of the ITO material of the stoichiometric structure is used and not formed. Compared with the case of the contact layer 150, the operating voltage of the light emitting device is lowered and the light output of the light emitting device is increased.

8 and 9 are graphs showing the experimental results of Table 2. FIG. VF3 shown in FIG. 8 represents the operating voltage in volts (V), and Po represents the light output in milliwatts (mW). In the graph represented by the circle, the hemisphere on the left represents Test 1, and the hemisphere on the right represents Test 2. Since FIGS. 8 and 9 show two halves of the entire area of the light emitting device, the curves of FIGS. 8 and 9 include Case 1 and Case 2.

Referring to FIG. 8 , which shows the operating voltage, it can be understood that the operating voltage in Test 2 is generally lower than the operating voltage in Test 1 . Referring to FIG. 9 showing the light output, it can be appreciated that the light output in Test 2 is generally higher than that in Test 1 .

10 and 11 are graphs showing the experimental results of Table 3. FIG. Similar to Figures 8 and 9, in the graphs represented by the circles, the hemisphere on the left represents Test 1 and the hemisphere on the right represents Test 2. The graphs of Figures 10 and 11 include Case 1 and Case 2.

Referring to FIG. 10 showing the operating voltage, it can be understood that the operating voltage in Test 2 is generally lower than the operating voltage in Test 1 . Referring to FIG. 11 showing the light output, it can be appreciated that the light output in Test 2 is generally higher than that in Test 1 .

FIG. 12 is a view illustrating the light emitting device package 10 according to the embodiment.

The light emitting device package 10 according to the embodiment includes: a main body 11 including a cavity; first and second lead frames 12 and 13 mounted on the main body 11; and the light emitting device 20 of the above-described embodiment mounted on the main body 11 and electrically connected to the first and second lead frames 12 and 13; and a molding portion 16, which is formed on the cavity.

The main body 11 may include a silicone material, a synthetic resin material, or a metal material. If the main body 11 is formed of a conductive material such as a metal material, the surface of the main body 11 may be coated with an insulating layer (although not shown in the drawings), so that the electrical connection between the first and second lead frames 12 and 13 is Short circuit can be prevented. A cavity may be formed in the package body 11, and the light emitting device 20 may be arranged at a bottom surface of the cavity.

The first lead frame 12 and the second lead frame 13 are electrically isolated from each other and supply current to the light emitting device 20 . The first lead frame 12 and the second lead frame 13 may increase luminous efficiency by reflecting light generated by the light emitting device 20 and dissipate heat generated by the light emitting device 20 to the outside.

The light emitting device 20 according to the above-described embodiments may be formed. The light emitting device 20 may be electrically connected to the first lead frame 12 and the second lead frame 13 via the wires 14 .

The light emitting device 20 may be fixed to the bottom surface of the package body 11 by a conductive paste (not shown). The molding part 16 may protect the light emitting device 20 by surrounding the light emitting device 20 . The fluorescent substance 17 may be included in the molding part 16 so that the fluorescent substance 17 can be excited by the light of the first wavelength region emitted from the light emitting device 20 to emit light of the second wavelength region.

The light emitting device package 10 may include one or more light emitting devices according to the above-described embodiments, but is not limited thereto.

The light emitting device and the light emitting device package described above can be used as a light source of a lighting system. For example, the light emitting device and the light emitting device package can be used for light emitting devices such as image display devices and lighting devices.

When the light emitting device or the light emitting device package is used as a backlight unit of an image display apparatus, the light emitting device or the light emitting device package may be used as an edge type backlight unit or a direct type backlight unit. When the light emitting device or the light emitting device package is used for a lighting apparatus, the light emitting device or the light emitting device package may be used as a light fixture or a built-in light source.

Although only a few embodiments are described above with respect to embodiments, various other embodiments are possible. The technical contents of the above-described embodiments can be combined in various forms unless they are incompatible, and thus can be implemented in a new embodiment.

Industrial Applicability

In the embodiment, the contact layer functions to smoothly inject holes from the second conductive type semiconductor layer to the active layer, so that the light emitting device of the embodiment can reduce the operating voltage and improve the light output. Therefore, the light emitting device is industrially applicable.

Claims (20)

1. A light-emitting device, comprising: substrate; a first-conductivity-type semiconductor layer disposed on the substrate; an active layer arranged on the first conductivity type semiconductor layer, a plurality of quantum well layers and a plurality of quantum barrier layers are alternately stacked in the active layer; a second conductive type semiconductor layer disposed on the active layer; a contact layer disposed on the second conductivity type semiconductor layer; a current spreading layer disposed on the contact layer; and a current blocking layer disposed on the second conductive type semiconductor layer, wherein the contact layer and/or the current spreading layer is formed to cover at least a portion of the current blocking layer and has a maximum intensity value of the diffracted X-ray beam when the Miller plane index is 400; The distance between the side surfaces of the current spreading layer and/or the contact layer and the side surfaces of the second conductive type semiconductor layer is in the range of 3 μm to 10 μm. 2 . The light emitting device according to claim 1 , wherein the current spreading layer is formed by deposition in an argon (Ar) atmosphere, and has a plurality of intensities of diffracted beams according to Miller plane index in an X-ray diffraction experiment. 3 . peak, and has the maximum intensity peak of the diffracted beam when the Miller plane index is 400. 3. The light emitting device of claim 1, wherein a ratio of the thickness of the current blocking layer to the total thickness of the contact layer and the current spreading layer is 2:1 to 5:1. 4. The light emitting device of claim 1, wherein the contact layer is formed of at least one of indium tin oxide (ITO), NiO, or NiAu. 5. The light emitting device of claim 1, wherein the contact layer has a thickness of 1 nm to 5 nm. 6. The light emitting device of claim 1, wherein the current spreading layer has a thickness of 20 nm to 70 nm. 7. The light emitting device of claim 1, further comprising: a reflective layer disposed under the substrate. 8. The light emitting device of claim 1, further comprising: a passivation layer, at least a portion of the passivation layer being disposed on the current spreading layer. 9. The light emitting device of claim 8, wherein a ratio of the thickness of the passivation layer to the thickness of the current spreading layer is 1.4:1 to 5:1. 10. The light emitting device of claim 1, wherein the contact layer is formed of indium tin oxide (ITO) having a non-stoichiometric structure lacking oxygen components. 11. The light emitting device of claim 1, wherein the current spreading layer is formed of an indium tin oxide (ITO) material. 12. The light emitting device of claim 11, wherein the current spreading layer has a non-stoichiometric structure. 13. The light emitting device of claim 1, further comprising: a first electrode disposed on the first conductivity type semiconductor layer; and a second electrode arranged on the second conductivity type semiconductor layer, Wherein, the current blocking layer is arranged between the second conductive type semiconductor layer and the second electrode. 14. The light emitting device of claim 13, wherein the current spreading layer is disposed between the current blocking layer and the second electrode. 15. The light emitting device of claim 13, wherein the current blocking layer has a thickness of 90 nm to 150 nm. 16. A light emitting device comprising: reflective layer; a substrate disposed on the reflective layer; a first-conductivity-type semiconductor layer disposed on the substrate; an active layer disposed on the first conductivity type semiconductor layer; a second conductive type semiconductor layer disposed on the active layer; a contact layer disposed on the second conductivity type semiconductor layer; a current spreading layer disposed on the contact layer and formed of indium tin oxide (ITO); the distance between the side surfaces of the current spreading layer and/or the contact layer and the side surfaces of the second conductivity type semiconductor layer is in the range of 3 μm to 10 μm; a passivation layer disposed on the current spreading layer; a first electrode disposed on the first conductivity type semiconductor layer; a second electrode disposed on the second conductive type semiconductor layer; and a current blocking layer disposed between the second conductive type semiconductor layer and the second electrode. 17. The light emitting device according to claim 16, wherein a mesa in which the second electrode is arranged is formed and is closest to the first electrode from a side surface of the first conductive type semiconductor layer of the mesa. The distance of the point of the side surface of the first conductive type semiconductor is 3 μm to 10 μm. 18. The light emitting device of claim 16, wherein an area of the current blocking layer is larger than an area of the second electrode. 19. The light emitting device of claim 16, wherein a ratio of the thickness of the current spreading layer to the thickness of the contact layer is 6:1 to 10:1. 20. A light emitting device package, comprising: a body, the body comprising a cavity; a lead frame mounted on the body; and The light emitting device according to any one of claims 1 to 19, the light emitting device being electrically connected to the lead frame.

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